Green power takes center stage

As they see the cost of energy rise, customers are demanding greater attention to the power consumption of their systems. Datacenter operators are focusing heavily on the operational cost of their systems and are prepared to pay to reap the benefits of lower electricity bills. This, in turn, is changing the way PSUs are designed – putting the focus not on the traditional peak efficiency but on how well the PSU performs across its output range.

A datacenter PSU is typically loaded at 20 percent of its rated power capacity. But the peak efficiency of many traditional PSU designs is only obtained when the PSU is running at 80 percent of its power capacity or more. The efficiency of traditional architectures can drop off rapidly as the load decreases. This is because switching losses begin to dominate the equation.

Although legislation is not yet targeting the data center, computer manufacturers have opted to move in the direction of greater efficiency for differentiation and also to offer customers operational cost savings. The highest-profile campaign is the 80 PLUS initiative. The idea behind 80 PLUS was first presented at the American Council for an Energy-Efficient Economy (ACEEE) Market Transformation Symposium and was quickly adopted as the basis for PSU efficiency marking by the Energy Star program. By the end of 2007, several hundred PSUs on the market were certified to the original 80 PLUS standard, which demanded PSUs could provide efficiency of at least 80 percent down to 20 percent of the rated peak load.

In 2008, the standard was revised to accommodate the demand for higher efficiency and greater cost savings. The Bronze, Silver and Gold classifications pushed efficiency at 20 percent load up to 82, 85 and 87 percent, respectively. In 2009, the Platinum category was added, which increased the 20 percent load efficiency to 90 percent.

The lifetime energy and cost savings for data centers simply by using these higher-efficiency PSUs are immense. By using 80 PLUS Gold-rated PSUs, a high-end can save between 30 MWh and 50 MWh during its lifetime. Because they offer higher efficiency, the servers also suffer less thermal stress and exhibit higher reliability from running cooler, which helps overall lifetime.

Using knowledge obtained from seven design centers around the world for standard and custom power supplies in the communications sector, Murata has become a world leader in the business for Gold and Platinum 1U front-end PSUs. The company provides products that offer 400W in the smallest 54mm-width housing up to 2800 W in a single power shelf. The S1U-3X shelf design supports for power ratings up to 6000 W.